Just Jackin' Around!
Not having any experiece with a jackshaft, I am free to try something stupid without feeling like a fool until it blows up on me. Being a basaically lazy person who doesn't want to have to tighten 2 chains, I came up with an idea for a floating jackshaft that allows you to tighten both chains at the same time.

To hold the bearings I welded a small sleeve on the outside of another piece of tubing and then mounted them to a couple of pivot arms. I cut the brackets out together and welded them to the tube with the pivot shaft in place.

Next, to mount the jackshaft assembly to the frame I cut a piece of wood to act as an alignment fixture to hold the shaft parallel to the axle.

With the axle and jackshaft held parallel I welded down the bushings on the frame. Now the whole thing is free to rotate. After the welds cooled, the pivot shaft was pretty tight. In theory, that's a good thing.

Voila! That's French for "well... there it is."

With the bearings pressed in and the shaft in place, all I have to do now is locate the motor, and a few hundred other things!

It's motor time!